多个三维薄板瞬变电磁响应的比较

Comparing Transient Electromagnetic Response of Multiple 3D Conductive Sheets

基于张量格林函数的体积分方程法对三维异常体进行瞬变电磁响应的正演模拟，首先在频率域内计算电磁场分量的频率域响应， 然后利用快速数字滤波技术将计算结果转换到时间域。通过对水平电偶极子源激发下５ 层地层模型中同一深度上２ 个和３ 个远源的水平导电薄板的瞬变电磁场响应的计算， 发现在长偏移距瞬变电磁测深中， 近源异常体总是比远源异常体表现出更大的异常， 因此远源异常体在勘探中容易被忽略或漏掉， 这是一个在资料采集和解释中需要注意的问题。

A forward modeling of three dimensional (3D) inhomogeneity is formulated with volume integral equation based on the tensor Green's function The response of electromagnetic components is calculated first in frequency domain and the result obtained is transformed to time domain by quick digital filtering From the EM responses of two and three horizontal conductive sheets in a five layered earth model excited by a horizontal electric dipole source, some conclusions are drawn that the 3D inhomogeneity near the source always gives an abnormality larger than that of the inhomogeneity far from the source in long offset transient electromagnetic survey where the inhomogeneity far from the source is neglected or omitted This is a problem to take data acquisition and explanation into account